The use of coherent or partially coherent sources can have advantages in display or illumination over standard incoherent sources (lamps) in that they can achieve higher brightness, better reliability, and larger color gamut. However, with this partial coherence comes the issue of speckle. Speckle is due to interference of the light on the screen or target that causes variations in intensity that can be seen by the observer or an instrument. These typically high frequency intensity variations are very undesirable for display or imaging applications.